Three-dimensional woven fabrics formed of three component yarns, i.e. longitudinal yarns, lateral yarns, and vertical yarns are used as woven or as the substrate for fiber-reinforced composite materials using matrices of resin or inorganic substance. Particularly, composite materials using the three-dimensional woven fabric have found utility as materials for heat-resistant parts in high-speed flying bodies such as rockets because they exhibit outstanding composite effects embracing shear strength and other mechanical properties and thermal properties as well. These materials are expected to find extensive utility in a wide spectrum of applications demanding various structures which feature light weight and high strength.
Concerning the method and apparatus for the formation of such three-dimensional woven fabric as described above, means of obtaining a perpendicularly intersecting woven fabric having longitudinal yarns and lateral yarns laid straight in parallel between series of vertical yarns (as disclosed in Japanese Pat. No. 922,489), means of obtaining a woven fabric having yarns in one direction displaced and zigzagged relative to a series of longitudinal yarns by alternately causing adjacent rows of longitudinal yarns to be translated to permit insertion of vertical yarns therebetween (as disclosed in Japanese Pat. No. 933,637), and means of laterally displacing and zigzagging the positions of both lateral and vertical yarns relative to rows of longitudinal yarns (as disclosed in Japanese Pat. No. 1,121,410) have been known to the art.
The means enumerated above as known to the art turn out to be methods or apparatuses which are useful for the formation of relevant textiles, namely a three-dimensional woven fabric having component yarns arranged in a perpendicularly intersecting pattern, a woven fabric having yarns in one selected direction displaced and zigzagged, and a woven fabric having yarns in two directions displaced and zigzagged relative to the yarns in the other remaining direction. They, however, are devoid of versatility and consequently incapable of enabling the condition of yarn arrangement to be freely varied or permitting their woven fabrics to be formed in various cross-sectional shapes as desired.
In U.S. Pat. No. 4,312,261, there is proposed an apparatus which is highly versatile in terms of arrangement of fibers and which permits a multiplicity of yarns or strands to be interwoven in various patterns by causing yarn feeders having yarns or strands wound up on bobbins to be suitably moved by electric commands and magnetic force. However, this apparatus is not intended to form a three-dimensional woven fabric by combining yarns of different dimensions as laid in perpendicularly intersecting X, Y, and Z directions. In terms of arrangement of fibers, the invention of this U.S. patent conceptually belongs to the category of the conventional braid formation. The product of this invention, therefore, differs in construction and combination of yarn components from the three-dimensional woven fabric. The invention is incapable of producing a three-dimensional woven fabric which possesses three-dimensional isotropy or anisotropy which is an important attribute to the substrate for component materials.